A broad field of GOP candidates are ramping up preparations for presidential runs in the wake of early maneuvering by establishment favorites Jeb Bush and Mitt Romney, kicking off the race for the 2016 Republican nomination at a breakneck speed.

At least 10 people were killed Wednesday when a bus carrying state prisoners skidded off an icy highway overpass in West Texas, slid down an embankment and collided with a passing train, a county sheriff said.